Yes, but this is really like trying to "undo" something that you have spoken. When you make a routing update, it takes place immediately (generally). You can

Yes, but this is really like trying to "undo" something that you have spoken. When you make a routing update, it takes place immediately (generally). You can only undo it by making another update (presuming of course that your first update didn't impair your ability to get more data through...). There are tools, like WANDL, that allow you to model your network and see what various changes or outages will look like in "real life". Of course, these simulations take time to setup and run. And, I've made simple routing updates before. I KNOW that this will work and I don't need to model it...